Technical Field
The present invention relates to a photopolymerizable composition, inkjet ink, a cartridge containing the ink, and a coated matter.
Background Art
Most of monomers for use in conventional photopolymerizable inkjet ink are toxic. In particular, (meth)acrylic acid esters, which are inexpensive and easily available, usually have high toxicity about skin sensitization potential indicating the degree of allergy upon contact with the skin. So far, this problem has remained unsolved.
These are required to have better robustness of a cured film of ink by ameliorating durability to scratch and low viscosity in order to avoid problems upon ink ejection even when the viscosity of ink is increased by mixing various materials such as pigments and additives.
In addition, when a photopolymerizable composition is used as a paint by brushing, it is possible to use organic solvents. However, such solvents are volatile and easily released into air. For this reason, it is preferable to use it as least as possible taking into account impact on environment and odor. If used as inkjet ink and mixed with an organic solvent having a high volatility, ink in nozzles to eject the ink becomes viscous by volatilization, resulting in adverse impact on ejection of ink, which is not preferable.
To reduce odor, it is good to simply reduce the amount of polymerization initiators. However, this sacrifice curing. That is, it is significantly difficult to obtain a cured matter while reducing smell. Some polymerization initiators produce no or little smell but is hazardous or has no or little solubility. Taking care of them in terms of safety and easiness of handling is furthermore difficult.